DNS
The Domain Name System (DNS) translates human-readable domain names (like example.com) into machine-readable IP addresses that computers use to connect.
§ 1 Definition
DNS is the phonebook of the internet. When you type a domain name into a browser, DNS resolves it to the IP address of the server hosting that site. Without DNS, you would have to remember numeric addresses like `192.0.2.1` for every website. DNS is hierarchical and decentralized. No single server holds the entire mapping. The system is organized into zones, each managed by authoritative name servers. When you change your hosting provider, you update DNS records (A, CNAME, MX, TXT) to point to the new server. DNS propagation is the time it takes for this change to spread across the internet. It can take minutes or hours depending on TTL (Time to Live) settings.
§ 2 How it works
When you enter a domain, your computer checks its local cache, then queries a recursive resolver (usually your ISP or a public resolver like Cloudflare 1.1.1.1). The resolver walks the DNS hierarchy: root servers, TLD servers (.com, .org), and authoritative name servers for the specific domain. The final response includes the IP address and a TTL indicating how long to cache the result.
§ 3 Record types
A (IPv4 address), AAAA (IPv6 address), CNAME (domain alias), MX (mail server), TXT (arbitrary text, used for verification and security), NS (name server), and CAA (certificate authority authorization). Misconfiguring DNS records is a common source of website downtime.
§ 4 Common misconception
Changing DNS records does not take 24 to 48 hours. That is the maximum propagation time, not the typical one. With low TTL values, changes can propagate within minutes. However, some ISPs cache aggressively and ignore TTL. The real bottleneck is often your local DNS cache, which you can flush immediately.
§ 5 Note
§ 6 In code
```bash
# Query DNS records using dig
dig example.com A
dig example.com MX
dig example.com CNAME
```§ 7 Common questions
- Q. What is DNS propagation?
- A. The time it takes for DNS changes to be updated across all DNS servers worldwide. Controlled by TTL values.
- Q. Can DNS affect website speed?
- A. Yes. A slow DNS resolver adds latency to every first-time request. Fast DNS providers like Cloudflare and Google reduce lookup times significantly.
- DNS translates domain names to IP addresses using a hierarchical, decentralized system.
- DNS records control where traffic, email, and verification go.
- Low TTL values speed up propagation but increase query volume. Choose wisely.
Atomic Glue manages DNS configurations as part of our Website Development services. Fast resolution, proper record types, and security extras like DMARC and CAA.
Get in touchThe Domain Name System (DNS) translates human-readable domain names (like example.com) into machine-readable IP addresses that computers use to connect.
Category: Web Development (also: Infrastructure)
Author: Atomic Glue Team
## Definition
DNS is the phonebook of the internet. When you type a domain name into a browser, DNS resolves it to the [IP address](/glossary/ip-address) of the server hosting that site. Without DNS, you would have to remember numeric addresses like `192.0.2.1` for every website. DNS is hierarchical and decentralized. No single server holds the entire mapping. The system is organized into zones, each managed by authoritative name servers. When you change your hosting provider, you update DNS records (A, CNAME, MX, TXT) to point to the new server. DNS propagation is the time it takes for this change to spread across the internet. It can take minutes or hours depending on TTL (Time to Live) settings.
## How it works
When you enter a domain, your computer checks its local cache, then queries a recursive resolver (usually your ISP or a public resolver like Cloudflare 1.1.1.1). The resolver walks the DNS hierarchy: root servers, TLD servers (.com, .org), and authoritative name servers for the specific domain. The final response includes the IP address and a TTL indicating how long to cache the result.
## Record types
A (IPv4 address), AAAA (IPv6 address), CNAME (domain alias), MX (mail server), TXT (arbitrary text, used for verification and security), NS (name server), and CAA (certificate authority authorization). Misconfiguring DNS records is a common source of website downtime.
## Common misconception
Changing DNS records does not take 24 to 48 hours. That is the maximum propagation time, not the typical one. With low TTL values, changes can propagate within minutes. However, some ISPs cache aggressively and ignore TTL. The real bottleneck is often your local DNS cache, which you can flush immediately.
## Note
DNS is not encrypted by default. DNS queries can be intercepted and modified (DNS spoofing). DNS over HTTPS (DoH) and DNS over TLS (DoT) add encryption. Cloudflare's 1.1.1.1 and Google's 8.8.8.8 both support encrypted DNS.
## In code
## Common questions Q: What is DNS propagation? A: The time it takes for DNS changes to be updated across all DNS servers worldwide. Controlled by TTL values. Q: Can DNS affect website speed? A: Yes. A slow DNS resolver adds latency to every first-time request. Fast DNS providers like Cloudflare and Google reduce lookup times significantly.
## Key takeaways
- DNS translates domain names to IP addresses using a hierarchical, decentralized system.
- DNS records control where traffic, email, and verification go.
- Low TTL values speed up propagation but increase query volume. Choose wisely.
## Related entries
- [IP Address](atomicglue.co/glossary/ip-address)
- [URL](atomicglue.co/glossary/url)
- [HTTP](atomicglue.co/glossary/http)
- [HTTPS](atomicglue.co/glossary/https)
Last updated June 2026. Permalink: atomicglue.co/glossary/dns